Biopolymers degradation process

However, in the case of biopolymers the processing window observed was very narrow, which in general lays in between the melting and degradation point of the material. For PLA the processing temperature observed was in between 175-190°C imder a screw speed of 40-60... 

The rates of adsorption and chain scission are affected by physicochemical properties of the substrate, such as the molecular weight, chemical composition, crystallinity, and surface area, and also by the inherent characteristics of the enzyme which can be measured in terms of its activity, stability, concentration, amino acid composition, and conformation. Moreover, environmental conditions such as pH and temperature also influence the activity of enzymes. The presence of stabilizers, activators, or inhibitors released from the polymer during the degradation process or additives that are leached out may also affect enzyme activity. Chemical modification of biopolymers may also affect the rate of enzymatic resorption since, depending on the degree of chemical modification, it may prevent the enzyme from recognizing the polymeric substrate. The rate of enzymatic resorption is limited by an enzyme saturation point. Beyond this enzyme concentration, no further increase in the rate of resorption is observed even when more enzyme is added. 

In nature, oxidoreductases - oxygenases, peroxidases and oxidases - are implicated in a wide variety of degradation processes of biopolymers and xenobiotics. It is not surprising, therefore, that metal complexes of biomimetic ligands such as porphyrins and phthalocyanines... 

Pyrolysis of biomass is defined as the chemical degradation of the biopolymers (cellulose, lignin and hemicellulose) constituting the wood fuel which initially requires heat. As can be seen in Figure 51, all reaction pathways making up the pyrolysis are not endothermic, which implies that some of the pyrolysis reactions generate heat. However, overall the pyrolysis process is endothermic. 

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